ISBN Validator
Validate ISBN-10 and ISBN-13 checksums and convert valid ISBN-10s to ISBN-13. Useful for library and publishing work. Everything runs in your browser.
FAQ
ISBN-10 vs ISBN-13?
The standard moved to 13 digits in 2007. ISBN-13 starts with 978/979; ISBN-10s convert by prefixing 978 and recomputing the check digit.
What does the trailing X mean?
ISBN-10 check values run 0–10; X is the Roman numeral for 10. ISBN-13 never uses X.
Does valid mean the book exists?
No—only the checksum format is verified. Look up actual bibliographic data in a national library database.
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